1. Technical Field
The present invention relates to a network communication technique, and more particularly to an IP multicast technique.
2. Related Art
At present, particularly in offices, printers, scanners, multifunction machines thereof, or the like are connected to an IP network (hereinafter, referred to as a “network”), and a PC or the like provided with a network communication apparatus (hereinafter, referred to as a “communication apparatus”) may perform printing by transmitting printing data to the printer or receive scanned image data from the scanner via the network.
At this time, as disclosed in JP-A-2004-120580 and SLP (Service Location Protocol), RFC2165 and RFC2608, there has been proposed a technique in which a search packet is transmitted from a communication apparatus in a multicast manner, and a response thereto is received, thereby searching for peripheral devices such as printers, scanners, multifunction machines thereof, or the like connected to a network.
IP addresses may be allocated to the communication apparatus and the peripheral device thereof connected to the network. There are mainly two address systems, IPv4 and IPv6, as the IP addresses, and either one of IPv4 or IPv6, or both of them, may be allocated to each device. Here, if the IPv6 address is allocated, a plurality of different IPv6 addresses may be allocated to one communication interface (hereinafter, referred to as a “communication I/F”). In addition, if IPv4 address is allocated as well, in a case where the communication apparatus includes a plurality of communication I/Fs, a different IPv4 address can be allocated for each communication I/F. In other words, there are cases where a plurality of different IP addresses may be allocated to one communication apparatus.
At this time, if a search packet is transmitted in a multicast manner, the respective IP addresses allocated to the communication apparatus are used as transmission sources, and thus a plurality of multicast packets are transmitted. That is to say, a number of multicast packets corresponding to the number of the IP addresses allocated to the communication apparatus are simultaneously transmitted. Here, the simultaneous transmission of the packets means that a large volume of packets are delivered within a very short time, and the packets are delivered substantially at the same time.
However, since the built-in type peripheral device such as a printer, a scanner, or a multifunction machine thereof has relatively small resources, the device may not be able to process the incoming plurality of multicast packets which are simultaneously transmitted from the communication apparatus. In other words, there is concern that the peripheral device may lose a portion of the multicast packets.
If a plurality of multicast packets are simultaneously transmitted from the communication apparatus, and a plurality of peripheral devices simultaneously return response packets to the multicast packets, there is concern that network traffic is increased, and this may have an adverse effect on the communication of other devices connected to the network.
In addition, this problem is not limited to the transmission of multicast packets. For example, the problem also influences a case where each IP address is used as a transmission source, and unicast packets are simultaneously transmitted.